Process for manufacturing hollow plastic bodies

Abstract

Process for manufacturing hollow plastic bodies, especially motor-vehicle fuel tanks, from an extruded parison of closed cross section, in which at least one cut is made in the parison which is then formed by molding.

1. A process of manufacturing a hollow body for receiving a liquid, comprising the steps of:
 extruding a parison;  
 cutting through said parison so as to form two portions separated by a cut; and  
 molding said two portions so as to form said hollow body for receiving said liquids,  
 wherein said step of cutting said parison comprises making at least two cuts in said parison so as to form two separate sheets.  
 
     
     
       2. The process of  claim 1 , wherein said hollow body is a tank and said liquid is a fuel. 
     
     
       3. The process of  claim 1 , wherein said step of molding comprises:
 pinching surfaces of said parison, and  
 hot fusion welding said surfaces.  
 
     
     
       4. The process of  claim 1 , wherein said step of cutting is Performed along a longitudinal direction. 
     
     
       5. The process of  claim 1 , wherein said step of extruding said parison comprises passing a composition of at least one thermoplastic melt through a die. 
     
     
       6. The process of  claim 1 , further comprising a step of cutting said parison in a transverse direction thereby obtaining a plurality of parisons. 
     
     
       7. The process of  claim 1 , wherein said step of molding comprises a step of holding apart said two portions of said parison and a subsequent step of bring said two portions together. 
     
     
       8. The process of  claim 7 , further comprising a step of inserting an object in said parison during said step of holding apart said two portions. 
     
     
       9. The process of  claim 8 , wherein said object is a preassembled structure. 
     
     
       10. The process of  claim 9 , wherein said preassembled structure is configured to anchor to an internal wall of said hollow body. 
     
     
       11. The process of  claim 8 , further comprising a step of controlling a position of said object with members, said members being coupled to said object and extending outside said parison while said object is inside said parison. 
     
     
       12. The process of  claim 11 , wherein said members melt during said molding step. 
     
     
       13. The process of  claim 1 , wherein said step of molding comprises a step of blowing gas within said parison, and a step of welding said two portions together. 
     
     
       14. The process of  claim 1 , wherein said step of molding comprises a step of bringing said two portions together and a step of welding said two portions together so as to form a joint leak-tight to said liquid. 
     
     
       15. The process of  claim 1 , further comprising a step of guiding said sheets with a guiding device. 
     
     
       16. A process of manufacturing a hollow body, comprising the steps of:
 extruding a multilayered parison comprising stacked layers fastened to each other;  
 cutting through said multilayered parison so as to form two portions separated by a cut; and  
 molding said two portions so as to form said hollow body,  
 wherein said step of cutting said multilayered parison comprises making at least two cuts in said multilayered parison so as to form two separate sheets.  
 
     
     
       17. The process of  claim 16 , wherein said hollow body is a fuel. 
     
     
       18. The process of  claim 16 , wherein said multilayered parison comprises at least one layer of a thermoplastic. 
     
     
       19. The process of  claim 16 , wherein said multilayered parison comprises at least one layer of polyethylene. 
     
     
       20. The process of  claim 16 , wherein said step of molding comprises:
 pinching surfaces of said parison, and  
 hot fusion welding said surfaces.  
 
     
     
       21. The process of  claim 16 , wherein said step of cutting is performed along a longitudinal direction. 
     
     
       22. The process of  claim 16 , wherein said step of extruding said multilayered parison comprises passing a composition of at least one thermoplastic melt through a die. 
     
     
       23. The process of  claim 16 , further comprising a step of cutting said parison in a transverse direction thereby obtaining a plurality of parisons. 
     
     
       24. The process of  claim 16 , wherein said step of molding comprises a step of holding apart said two portions of said parison and a subsequent step of bringing said two portions together. 
     
     
       25. The process of  claim 24 , further comprising a step of inserting an object in said parison during said step of holding apart said two portions. 
     
     
       26. The process of  claim 25 , wherein said object is a preassembled structure. 
     
     
       27. The process of  claim 26 , wherein said preassembled structure is configured to anchor to an internal wall of said low body. 
     
     
       28. The process of  claim 25 , further comprising a step of controlling a position of said object with members, said members being coupled to said object and extending outside said parison while said object is inside said parison. 
     
     
       29. The process of  claim 28 , wherein said members melt during molding step. 
     
     
       30. The process of  claim 16 , wherein said step of molding comprises a step of blowing gas within said parison, and a step of welding said two portions together. 
     
     
       31. The process of  claim 16 , wherein said step of molding comprises a step of bringing said two portions together and a step of welding said two portions together so as to form a leak-tight joint. 
     
     
       32. A process of manufacturing a fuel tank, comprising the steps of:
 extruding a parison;  
 cutting through said parison so as to form two portions separated by a cut; and  
 molding said two portions so as to form said fuel tank,  
 wherein said step of cutting said parison comprises making at least two cuts in said parison so as to form two separate sheets.  
 
     
     
       33. The process of  claim 32 , further comprising a step of positioning fuel tank accessories between said two portions prior to a step of bringing said two portions together. 
     
     
       34. The process of  claim 32 , wherein said step of molding comprises:
 pinching surfaces of said parison, and  
 hot fusion welding said surfaces.  
 
     
     
       35. The process of  claim 32 , wherein said step of cutting is performed along a longitudinal direction. 
     
     
       36. The process of  claim 32 , wherein said step of extruding said parison comprises passing a composition of at least one thermoplastic melt through a die. 
     
     
       37. The process of  claim 32 , further comprising a step of cutting said parison in a transverse direction thereby obtaining a plurality of parisons. 
     
     
       38. The process of  claim 32 , wherein said step of molding comprises a step of holding apart said two portions of said parison and a subsequent step said two portions together. 
     
     
       39. The process of  claim 38 , further comprising a step of inserting an object in said parison during said step of holding a part said two portions. 
     
     
       40. The process of  claim 39 , wherein said object is a preassembled structure. 
     
     
       41. The process of  claim 40 , wherein said preassembled structure is configured to anchor to an internal wall of said fuel tank. 
     
     
       42. The process of  claim 39 , further comprising a step of controlling a position of said object with members, said members being coupled to said object and extending outside said parison while said object is inside said parison. 
     
     
       43. The process of  claim 42 , wherein said members melt during said molding step. 
     
     
       44. The process of  claim 32 , wherein said step of molding comprises a step of blowing gas within said parison, and a step of welding said two portions together. 
     
     
       45. The process of  claim 32 , wherein said step of molding comprises a step of bringing said two portions together and a step of welding said two portions together so as to form a leak-tight joint.